The present invention relates to a method and apparatus for converting chemical energy to electrical energy for power usage or gas-sensing applications. More specifically, the present invention describes a fuel cell that uses a single gas mixture, such as methane and air, to achieve the spontaneous conversion of chemical energy into electrical energy.
A fuel cell is an electrochemical device that continuously converts the chemical energy of a fuel, such as methane, and an oxidant, such as molecular oxygen, to electrical energy. The fuel and oxidant are continuously supplied to the fuel cell from an external source. The fuel and oxidant are supplied to chambers of the fuel cell which are separated by an electrolyte barrier. This electrolyte barrier can be liquid or molten electrolyte, however, the present invention is concerned with solid electrolytes.
Since fuel cells produce power by an electrochemical reaction rather than a thermal process, they are not subject to the Carnot cycle limitation of combustion engines. This allows for a highly efficient conversion of chemical energy to electric energy. In addition, fuel cells are very clean and quiet in operation as there are no moving parts and the by products from the cell operation are carbon dioxide and water. Furthermore, it is possible to recover the waste heat generated from a fuel cell producing even greater efficiencies.
A conventional solid-state electrolyte fuel cell uses solid non-porous metal oxide electrolyte, such as zirconium oxide as the electrolyte material. With this type of electrolyte, ionic conductivity takes place by the migration of oxygen ions through the lattice of the crystal. Typically, these zirconia cells are operated at elevated temperatures (e.g. 900.degree.C.-1000.degree. C.). Inside the conventional fuel cell the fuel and oxidation gas are required to be separated from each other by the non-porous solid electrolyte which needs two separate sets of gaseous operation equipment. The present invention solves these problems in a unique and novel manner.